(b) : In an isolated system, there is neither exchange of energy nor matter between the system and surrounding. For a spontaneous process in an isolated system, the change in entropy is positive, i.e. ΔS > 0.
Most of the spontaneous chemical reactions are exothermic. A number of endothermic reactions are spontaneous e.g. melting of ice (an endothermic process) is a spontaneous reaction. The two factors which are responsible for the spontaneity of a process are
(i) tendency to acquire minimum energy
(ii) tendency to acquire maximum randomness.
